Field of the Invention
The present invention relates to a power supply system for an outboard motor, an outboard motor boat, and an outboard motor.
Description of the Background Art
A power supply system for an outboard motor is known in general. Such a power supply system for an outboard motor is disclosed in U.S. Pat. No. 5,681,193 and Japanese Patent Laying-Open No. 2001-128388, for example.
The aforementioned U.S. Pat. No. 5,681,193 discloses a marine propulsion device (a power supply system for an outboard motor) including an engine, an alternator that generates a first alternating-current voltage and a second alternating-current voltage, and a rectifier/regulator that transforms the first alternating-current voltage and the second alternating-current voltage into a first direct-current voltage required by an engine accessory and a second direct-current voltage required by a battery, respectively.
The aforementioned Japanese Patent Laying-Open No. 2001-128388 discloses a charging system for a small boat (a power supply system for an outboard motor) including an engine, a power generator driven by rotation of the engine, a propeller battery and an accessory battery charged with electric power output from the power generator, and a regulator that regulates the electric power output from the power generator. In this charging system for a small boat according to Japanese Patent Laying-Open No. 2001-128388, the propeller battery and the accessory battery are powered by a common voltage regulated by the regulator.
In a power supply system for the conventional marine propulsion device described in the aforementioned U.S. Pat. No. 5,681,193, a voltage is transformed into a prescribed direct-current voltage required by the battery through the rectifier/regulator. When the power consumption of an electrical component is increased so that a required power generation amount is increased, therefore, it is necessary to increase a current due to the constant voltage in order to increase electric power of transmission. In other words, the voltage is restricted by a battery voltage during electric power transmission. In this case, it is difficult to make the current larger than a current transmittable according to the diameter of a transmission line and transmit more electric power.
In the charging system for a small boat according to the aforementioned Japanese Patent Laying-Open No. 2001-128388, the regulator supplies electric power of a common regulated voltage to the propeller battery and the accessory battery. Also in the charging system for a small boat according to the aforementioned Japanese Patent Laying-Open No. 2001-128388, a voltage is restricted by a battery voltage during electric power transmission, similarly to in the power supply system for the marine propulsion device described in the aforementioned U.S. Pat. No. 5,681,193, and hence it may be difficult to transmit more electric power. In order to transmit more electric power, the diameter of a transmission line is conceivably increased. If the diameter of the transmission line is increased, however, the volume and weight of the transmission line is increased. In general, thus, a power supply system for an outboard motor, an outboard motor boat, and an outboard motor each enabling an increase in electric power of transmission while significantly reducing or preventing an increase in the diameter of the transmission line are desired.